Hydropneumatic absorbing device for railway rolling stock

ABSTRACT

A hydropneumatic absorbing device used in a railway rolling stock, comprising a cylinder having a movable cylinder mounted at the open end thereof and accommodating a floating piston and connected with a piston provided with through openings. Secured near the bottom of the cylinder is a partition forming together with the piston a space to be filled with working liquid, and together with the bottom of the cylinder - an additional chamber accommodating an additional piston. The partition is provided with through openings through which the working liquid is supplied into the additional chamber and displaces the additional piston. The spaces adjacent to the bottoms of the two cylinders are filled with compressed gas and the pressure in one of the spaces is several times greater than the pressure in the other space.

United States Patent Karakashian et al.

1151 3,656,632 1451 Apr. 18, 1972 [54] HYDROPNEUMATIC ABSORBING DEVICEFOR RAILWAY ROLLING STOCK [22] Filed: Apr. 13,1970

[21] Appl.No.: 27,796

[52] U.S.Cl .213/43, 188/317,213/223, 267/64 R, 188/316 151] mu..B61g9/l6,B61g 11/12 [58] Field of Search ..213/8, 43, 223; 267/64 R,43, 267/64 A; 188/313, 316, 317, 321

Primary Examiner-Drayton E. Hofiman Attorney-Waters, Roditi, Schwartz &Nissen [57] ABSTRACT A hydropneumatic absorbing device used in a railwayrolling stock, comprising a cylinder having a movable cylinder mountedat the open end thereof and accommodating a floating piston andconnected with a piston provided with through openings. Secured near thebottom of the cylinder is a partition fonning together with the piston aspace to be filled with working liquid, and together with the bottom ofthe cylinder an additional chamber accommodating an additional piston.The partition is provided with through openings through which theworking liquid is supplied into the additional chamber and displaces theadditional piston. The spaces adjacent to the bottoms of the twocylinders are filled with compressed gas and the pressure in one of thespaces is several times greater than the pressure in the other space.

3 Claims, 6 Drawing Figures PATENTEU APR 1 8 I972 SHEET 1 [IF 3'PATENTEU APR 1 81912 SHEET 3 [1F 3 I-IYDROPNEUMATIC ABSORBING DEVICEFOR RAILWAY ROLLING STOCK BACKGROUND 1. Field of the Invention Thisinvention relates to hydropneumatic devices for absorbing kinetic energyof relatively movable bodies and more particularly automatic couplersfor railway rolling stock.

2. Description of the Prior Art Known in the art are hydropneumaticabsorbing devices provided with a cylinder which accommodates anothermovable cylinder of a smaller diameter, disposed at the open sidethereof, the bottom of the latter cylinder interacting with the movableportion of an automatic coupling of'a railway rolling stock. The movablecylinder accommodates a floating piston disposed inside thereof, and atits open side is connected with a piston having through openings, forthe working liquid to flow from the space disposed between the bottom ofsaid piston and a partition secured in the cylinder near the bottomthereof, into a space disposed at the other side of the piston. Providedbetween the partition and the bottom of the cylinder is an additionalchamber accommodating an additional piston, the latter being displacedby meansof a hollow rod connected therewith and interacting with apiston connected with the movable cylinder in the course of movement ofthe latter.

The space confined between the bottom of the cylinder and the additionalpiston, as well as the spacedisposed between the bottom of the movablecylinder and the floating piston, are filled with compressed gas. Thepressure of the compressed gas in the space disposed between thecylinder bottom and the additional piston by several times exceeds thepressure of the compressed gas contained in the space confined by thebottom of the movable cylinder and the floating piston.

To protect the cylinder from excessive pressure, the device is providedwith a safety valve arranged in the hollow rod. During its return strokethe movable cylinder is braked by means of a throttle valve (see, forexample, U.S. Pat. No. 3,l93,1 12; July 6, 1965).

With the longitudinal force preset, the absorbing capacity of thehydropneumatic absorbing device depends directly upon the stroke of thepiston connected with the movable cylinder of the device. In theafore-described hydropneumatic absorbing device the piston stroke equals70 mm., and its absorbing capacity is equal to l0,000-l2,000 kgm, which,with the preset longitudinal force equalling 200 tons, provides for theabsorption of the kinetic energy of collision of four-axle cars movingat a speed of 12 km/hr.

Such absorbing capacity proves insufficient to damp the kinetic energyof collision of six axle cars moving at the aforesaid speed, or ofcollision of four-axle cars moving at speeds considerably exceeding 12km/hr.

SUMMARY OF THE INVENTION The main object of the invention is theprovision of a hydropneumatic absorbing device that possesses a greaterabsorbing capacity owing to an increased stroke of the movable cylinder,the overall dimensions of the device and the allowable longitudinalforce being the same.

This object is accomplished in a hydropneumatic absorbing device used ina railway rolling stock and comprising a cylinder having a movablecylinder disposed at the open side thereof and accommodating a floatingpiston, said movable cylinder interacting with the movable parts of theautomatic coupling, being connected with a piston provided with throughopenings overlapped by a throttle valve during the piston return stroke,a partition being secured near the bottom of the cylinder, together withthe piston said partition forming a space filled with working liquid andtogether with the bottom of the cylinder said partition forming anadditional chamber, accommodating an additional piston which movesduring the movement of the movable cylinder, the spaces adjacent to thebottoms of the cylinders being filled with compressed air, the pressureof the air in one space exceeding by several times the pressure of theair in the other space; according to the present invention, thepartition is provided with openings to communicate the space filled withthe working liquid with the additional chamber, and the additionalpiston is made floating.

It is expedient to secure a rod on the partition along the cylinderaxis, said rod having a cross section decreasing towards its free endportion and passing through the opening in the piston, thus controllingthe discharge of the working liquid through this opening.

Such a control of the discharge of the working liquid provides for astill greater absorbing capacity of the hydropneumatic absorbing device.

The hydropneumatic absorbing device in accordance with the presentinvention, possesses an absorbing capacity of up to 20,000 kgm, whichmakes it possible to absorb the kinetic energy produced by the collisionof four-axle cars moving at a speed of up to km/hr, or by the collisionof six axle cars 0 moving at a speed of up to 16 km/hr, the allowablelongitudinal force being equal to 200 tons.

BRIEF DESCRIPTION OF THE DRAWING The following description of a specificexemplary embodiment of the present invention is given with reference tothe accompanying drawings in which:

FIG. 1 is a longitudinal section of a hydropneumatic absorbing device,according to the present invention;

FIG. 2 is a prespective view of a rod used for controlling the dischargeof the working liquid;

FIG. 3 is a sectional view showing the disposition of the device membersat the beginning of the working stroke;

FIG. 4 is a view similar to FIG. 4 in the intermediate position of theworking stroke; and

FIG. 5 is a view similar to FIG. 4 at the beginning of the returnstroke; and

FIG; 6 is a graph of the operation of the hydropneumatic absorbingdevice.

DETAILED DESCRIPTION The hydropneumatic absorbing device comprises acylinder 1 having a movable cylinder 2 mounted at the open side thereof,the bottom of the movable cylinder 2 interacting with movable parts ofan automatic coupling device (not shown in the drawing). 0n the outersurface of the movable cylinder 2 are grooves accommodating packingrings 4 and bronze inserts 5. Disposed inside the movable cylinder 2 isa floating piston 6 having rubber packing rings 7 and a hydraulicpacking which consists of a small piston 8 housed in a chamber 9 filledwith oil and communicating via passages 10 with annular grooves 11 onthe outer surface of the floating piston 6.

The side of the movable cylinder 2, opposite to the bottom 3 is rigidlyconnected with a piston 12 having through openings 13 and a centralopening 14.

The piston 12 is provided with an annular recess 15 accommodating athrottle valve 16 used to overlap the openings 13 during the returnstroke of the piston 12. The displacement of the throttle valve 16 islimited by a ring 17.

Rigidly secured in the cylinder 1 near its bottom 18 is a partition 19which together with the piston 12 forms a space 20 filled with workingliquid introduced through an opening in the cylinder 1 and closed by aplug 21. The partition 19 forms an additional chamber 22 with the bottom18 of the cylinder 1. This chamber accommodates an additional piston 23with packing rings 24, the additional piston 23 being made floating.

The partition 19 is provided with openings 25 communicating theadditional chamber 22 with the space 20.

Secured in the middle portion of the partition 19 is a rod 26 having avarying cross section decreasing towards its free end, said rod passingthrough the central opening 14 in the piston 12.

The varying cross section of the rod 26 is obtained due to the fact thatthe rod has four slots 27 (FIG. 2) therein having the same width, thedepth of the slots decreasing in the direction towards the secured endportion of the rod.

The body of the rod 26 accommodates a safety valve 28 (FIG. 1) which, incase the pressure of the liquid exceeds an allowable value, communicatesthe space 20 with a space disposed between the piston 12 and thefloating piston 6.

The space 29 disposed in the movable cylinder 2 between the bottom 3thereof and the floating piston 6 is filled with compressed gas suppliedvia a valve 30, the pressure of the gas being approximately equal to 50kg/cm A space 31 disposed between the bottom 18 of the cylinder 1 andthe additional piston 23 is filled via a valve 32 with compressed gasunder the pressure of 15 kglcm The hydropneumatic absorbing devicefunctions as follows:

When two cars collide, the movable parts of the automatic coupling (notshown in the drawing) interact with the bottom 3 of the movable cylinder2 by moving it inside the cylinder 1. The piston 12 connected with thecylinder 2, moves together with the latter and forces the working liquidout of the space 20 into the additional chamber 22, as shown in FIG. 3,since the pressure of the compressed gas in the space 31 is considerablysmaller than that of the compressed gas contained in the space 29. Theworking liquid flows from the space 20 into the additional chamber 22until the additional piston 23 displaced by the liquid thrusts againstthe bottom 18 of the cylinder 1.

During further movement of the piston 12, the working liquid startsflowing via the openings 13 in the piston 12 and via the slots 27 of therod 26 into a space 33 formed between the piston 12 and the floatingpiston 6, as shown in FIG. 4, and displaces the floating piston 6.

The working liquid continues to flow in the afore-described manner untilthe piston 12 reaches the partition 19 and all the working liquid flowsinto the space 33. The length of the complete stroke of the piston is120 mm.

The employment of the rod 26 having a varying cross section is necessaryto maintain a required hydraulic resistance of the working liquid whenthe rate of the piston 12 displacement is decreased.

The return stroke of the piston 12 starts only when the force exerted bythe movable parts of the automatic coupling (not shown in the drawing)upon the bottom 3 of the movable cylinder 2 is smaller than the totalforce of the compressed gas in the spaces 31 and 29.

The floating pistons 6 and 23 and the piston 12 are retracted in reverseorder from that previously described, as shown in FIG. 5, under theaction of the compressed gas contained in the spaces 31 and 29. Duringthis stroke the throttle valve 16 under the pressure of the workingliquid closes the through openings 13 having constant cross sections,which contributes to the retarded motion of the piston 12 during itsreturn stroke.

In order to limit the displacement of the movable cylinder 2 during itsreturn stroke, the cylinder 1 is provided with a stop I 34 fashioned asa nut.

The diagram shown in FIG. 6 shows the variation of force Q (longitudinalforce) depending on stroke S of the piston.

Line a shows changes of the force during the compression of the gas inthe space 31; line b shows changes of the force Q, when the gascontained in the space 29 is slowly compressed, and line c shows changesof this force during the gas dynamic compression which takes place inaccordance with the adiabatic conditions with a polytropic index ofll.3; line d shows changes in the dynamic resistance of the liquid.

In the zone 0-1 the liquid flows from the space 20 into the additionalchamber 22, the gas contained in the space 31 is compressed, and line ashows in the diagram changes of the force Q during the compression ofthe gas in this space.

At the point 1 the space 29 is actuated, line c showing in the diagramthe change of the force 0 during the compression of thelglas in thisspace.

e dynamic force rises up to point II. At this time the speed of movementstarts decreasing, however, due to the dynamic force of the compressedgas in the space 29 and an increase in the hydraulic resistance of theliquid taking place while the latter is flowing out through decreasingcross-sections of the slots 27 of the rod 26, the characteristic isequalized before the point III, and the changes in the totalhydrodynamic force are characterized by a curve shown by line e. Thus,the efficient operation of the hydropneumatic absorbing device isprovided in the course of its whole movement.

In the diagram, shown in FIG. 6, the cross hatched area at the leftshows the operation of the hydropneumatic absorbing device used to dampimpacts, with a piston stroke equalling 70 mm, whereas the additionalshows an additional increase in the absorbing capacity of the proposeddevice taking place due to its greater length increased up to 120 mm andto the employment of the rod having a varying cross-section.

The hydropneumatic absorbing device according to the present inventionprovides for an increased absorbing capacity of up to 20,000 kgm, whichallows shunting operations with cars having a speed of collision of upto 20 km/hr.

Furthermore, this embodiment of the hydropneumatic absorbing deviceprovides for damping of multiple shocks and impacts developed when atrain starts moving, is moving along a prolonged slope, or is braked.

What is claimed is:

1. A hydro-pneumatic absorbing device for absorbing kinetic energy ofbodies having relative motion and particulady for automatic couplers forrailway rolling stock, said device comprising a first cylinder havingopen and closed ends; a movable cylinder adapted for engaging themovable parts of an automatic coupling of the rolling stock, saidmovable cylinder being slidable in said first cylinder at said open endthereof; said movable cylinder having a closed end projecting from theopen end of the first cylinder; a floating piston disposed in saidmovable cylinder; a second piston provided with through openings rigidlyconnected with said movable cylinder; a throttle valve disposed in saidsecond piston and overlapping said through openings during piston returnstroke; a partition provided with through openings, said partition beingsecured in said first cylinder near the closed end thereof and formingtogether with said second piston a chamber adapted to be filled withworking liquid and together with the closed end of said first cylinderan additional chamber; and an additional floating piston disposed insaid additional chamber and being displaced in the course of movement ofsaid movable cylinder, said additional floating piston defining a spacewith the closed end of the first cylinder, the first floating pistondefining a space with the closed end of the movable cylinder, saidspaces being filled with compressed gas, the pressure of the gas in oneof the spaces exceeding by several times the pressure in the otherspace.

2. A hydropneumatic absorbing device as claimed in claim 1 comprising arod secured to said partition and extending along the axis of thecylinder, said rod having a varying cross section which decreases in adirection away from said partition, said second piston having an openingin which said rod travels and controls discharge of the working liquidthrough said opening.

3. A hydropneumatic absorbing device as claimed in claim 2 wherein saidrod has a passageway for providing communication between the chamberfilled with working liquid and the opening in the second piston, and asafety valve in said passageway.

1. A hydro-pneumatic absorbing device for absorbing kinetic energy ofbodies having relative motion and particularly for automatic couplersfor railway rolling stock, said device comprising a first cylinderhaving open and closed ends; a movable cylinder adaptEd for engaging themovable parts of an automatic coupling of the rolling stock, saidmovable cylinder being slidable in said first cylinder at said open endthereof; said movable cylinder having a closed end projecting from theopen end of the first cylinder; a floating piston disposed in saidmovable cylinder; a second piston provided with through openings rigidlyconnected with said movable cylinder; a throttle valve disposed in saidsecond piston and overlapping said through openings during piston returnstroke; a partition provided with through openings, said partition beingsecured in said first cylinder near the closed end thereof and formingtogether with said second piston a chamber adapted to be filled withworking liquid and together with the closed end of said first cylinderan additional chamber; and an additional floating piston disposed insaid additional chamber and being displaced in the course of movement ofsaid movable cylinder, said additional floating piston defining a spacewith the closed end of the first cylinder, the first floating pistondefining a space with the closed end of the movable cylinder, saidspaces being filled with compressed gas, the pressure of the gas in oneof the spaces exceeding by several times the pressure in the otherspace.
 2. A hydropneumatic absorbing device as claimed in claim 1comprising a rod secured to said partition and extending along the axisof the cylinder, said rod having a varying cross section which decreasesin a direction away from said partition, said second piston having anopening in which said rod travels and controls discharge of the workingliquid through said opening.
 3. A hydropneumatic absorbing device asclaimed in claim 2 wherein said rod has a passageway for providingcommunication between the chamber filled with working liquid and theopening in the second piston, and a safety valve in said passageway.